bitlist 0.8.0

Pure-Python library for working with bit vectors.

Pure-Python library for working with bit vectors.

Purpose

This library allows programmers to work with a native representation of bit vectors within Python.

Installation and Usage

This library is available as a package on PyPI:

python -m pip install bitlist

The library can be imported in the usual way:

import bitlist
from bitlist import bitlist

Examples

This library makes it possible to construct bit vectors from a variety of representations (including integers, bytes-like objects, strings of binary digits, lists of binary digits, and other bit vectors). Integer arguments are converted into a big-endian binary representation:

>>> bitlist(123)
bitlist('1111011')
>>> bitlist(bytes([255, 254]))
bitlist('1111111111111110')
>>> bitlist('101')
bitlist('101')
>>> bitlist([1, 0, 1, 1])
bitlist('1011')
>>> bitlist(bitlist('1010'))
bitlist('1010')

The length parameter can be used to specify the length of the bit vector:

>>> bitlist(bytes([123]), 16)
bitlist('0000000001111011')
>>> bitlist(16, 64)
bitlist('0000000000000000000000000000000000000000000000000000000000010000')
>>> bitlist(bitlist(123), 8)
bitlist('01111011')

If the length parameter has a value that is less than the minimum number of bits that would be included according to the default constructor behaviors, the bit vector is truncated on the left-hand side to match the specified length:

>>> bitlist(bytes([123]), 7)
bitlist('1111011')
>>> bitlist(bytes([123]), 4)
bitlist('1011')
>>> bitlist(bytes([123]), 2)
bitlist('11')
>>> bitlist(bytes([123]), 0)
bitlist('')

Concatenation, partitioning, subscription and slicing, shift and rotation, comparison, and logical operations are also supported by instances of the bitlist class. The larger example below – a bitwise addition function – illustrates the use of various operators supported by instances of the bitlist class:

from bitlist import bitlist

def add(x, y):
    """Bitwise addition algorithm."""
    r = bitlist(0)

    # Upper bound is not inclusive.
    # Use negative indices for big-endian interface.
    carry = 0
    for i in range(1, max(len(x), len(y)) + 1):
        r[-i] = (x[-i] ^ y[-i]) ^ carry
        carry = (x[-i] & y[-i]) | (x[-i] & carry) | (y[-i] & carry)
    r[-(max(len(x), len(y)) + 1)] = carry

    return r

The testing suite test/test_bitlist.py contains additional examples of bitwise arithmetic operations implemented with the help of this library.

Development

All installation and development dependencies are managed using setuptools and are fully specified in setup.py. The extras_require parameter is used to specify optional requirements for various development tasks. This makes it possible to specify additional options (such as docs, lint, and so on) when performing installation using pip:

python -m pip install .[docs,lint]

Documentation

The documentation can be generated automatically from the source files using Sphinx:

python -m pip install .[docs]
cd docs
sphinx-apidoc -f -E --templatedir=_templates -o _source .. ../setup.py && make html

Testing and Conventions

All unit tests are executed and their coverage is measured when using pytest (see setup.cfg for configuration details):

python -m pip install .[test]
python -m pytest

The subset of the unit tests included in the module itself can be executed using doctest:

python bitlist/bitlist.py -v

Style conventions are enforced using Pylint:

python -m pip install .[lint]
python -m pylint bitlist ./test/test_bitlist.py

Contributions

In order to contribute to the source code, open an issue or submit a pull request on the GitHub page for this library.

Versioning

Beginning with version 0.3.0, the version number format for this library and the changes to the library associated with version number increments conform with Semantic Versioning 2.0.0.

Publishing

This library can be published as a package on PyPI by a package maintainer. First, install the dependencies required for packaging and publishing:

python -m pip install .[publish]

Remove any old build/distribution files. Then, package the source into a distribution archive using the wheel package:

rm -rf dist *.egg-info
python setup.py sdist bdist_wheel

Finally, upload the package distribution archive to PyPI using the twine package:

python -m twine upload dist/*